Waterproof wrapping cloth



Patented Get. 1, 1929 UNITED STATES CHARLES H. PANTHEN, OI SCI-IENECTADY,

PATENT OFFICE NEW YORK, AssrGNoR 'ro GENERAL ELEC- TRIC COMPANY, A CORPPRATI ON OF NEW YORK 'wa'rnnrnoor WRAPPING CLOTH No Drawing.

My present invention relatesvto wrapper- In the shipment of machines, and especially dynamo-electric machines, it is imperative that they should be completed protected from action of the weather. This is particularly 1o true when such machines are shipped toforeign points where they are frequently allowed to stand exposed on docks and'wharfs for prolonged periods of time. I have found that a relatively inexpensive and yet highly eflicientwaterproof wrapper suitable for the above purpose may be obtained by impregnating and coating unbleached muslin or sheeting with a mixture of a soft, sticky pitch, such as roofing pitch, and mineral oil. Such a 2 treatment renders the woven fabric completely waterproof, yet flexible and entirely free from brittleness. At the same time the strength of the woven fabric is unimpaired.

In carrying my invention into effect about 7 to 7% pounds of nondrying oil, such as ordinary. refined mineral oil are added to about 100 pounds of roofing pitch and the mixture heated in a tank or vat to a temperature of about 95 C. A strong, open weave fabric .30 is then immersed in the mixture and slowly drawn through the vat to thoroughly fill or impregnate the fibres of the woven material and provide thereon a relatively thin surface layer of the mixture. When the fabric is drawn out of the vat it is cooled by an air blast and then sprinkled with sawdust, after which it is rolled up for future use. In order to obtain the best results, the temperature of the mixture throughout the vat should be maintained closed to the figure indicated, as above this point the fabric may be destroyed by burning and the mixture is too thin to properly waterproof the fabric. Below the temperature indicated the mixture is too thick to penetrate into the fabric. It is further desirable that sawdust, and preferably hard wood sawdust, should be applied to the entire surface of the impregnated cloth as otherwise, due to the stickiness of the waterproofing material, there may be a tendency, when Application filed June 25,

1926. Serial No. 118,601.

unrolling the cloth, for a portion of the uncovered pitch to become attached to the su- 'perimposed adjacent surface, and thereby begome partially detached from the fabric ase.

The pitch em loyed is generally known to the trade as nchor brand roofing pitch (Barrett Manufacturing Company). It is a very soft, sticky material and will flow or rather creep at room temperature; that is, if

the pitch is placed on an inclinedboard, it-will creep very slowly thereon at a temperature of approximately 20 to 22 C. A chemical analysis-of the pitch shows that its drip point is between 7 8 and 81 (1, that its penetration is 1.3 m. m.; that it is 100% soluble in carbon bisulphide that its sulphur content is 5.13 and its ash content 8.12. By the expression drip point I mean the temperature at which a small amount of.pitch placed on the end p I of a rod will become liquid and form a drop. The penetration value was determined by a standard penetrometer and is a measure of the hardness of the pitch. It is the extent .to which a standard needle of given cross section will travel into the pitch in a certain time period, undera certain pressure, the time and pressure in the present case being 30 seconds and 100 grams respectively.

The nondrying oil employed preserves-the so softness of the mixture and prevents hardening of the pitch. While the amount of oil may be varied with the degree of hardness of the pitch, the pitch employed should always be what is commonly known as a soft pitch, as distinguished from hard asphaltic substances, such as gilsonite; that is, itshouldhaveapenetration of approximately 1.33 m. m. and. should creep slowly at room temperature as specified above It is further essential that the pitch should be sticky or adhesive in character since a pitch which is soft, but lacking in adhesive qualities will prove inadequate as waterproofing material.

WVhile various woven fabrics might be employed as a base for my wrapper material, I have found that an open weave unbleached muslin or sheeting gives very satisfactory results. This material, when about 36 inches wide and averaging about 4 to 4 yards to the pound, is strong and durable, and when impregnated and coated with my waterproofing composition, remains flexiblehand waterproof indefinitely. The wrapper material may be given sharp bends or folded without causing the materialto crack or lose .its waterproofing qualities. It furthermore has the'property of being self sealing, that is if the cloth is folded and end portions thereof, which maybe free from sawdust, are pressed together, a waterproof joint is formed. Also if a nail is drawn through the impregnated and coated fabric and left there water will not penetrate the cloth at that point.

What I claim as new and desire to secure by Letters Patent of the United States is 1. A flexible waterproof sheet Wrapping material comprising a Woven fabric base impregnated with a mixture consisting of about one hundred parts by Weight of soft adhesive pitch and about seven parts by Weight of mineral oil which is adapted to prevent hardening of the pitch.

2. A flexible Waterproof sheet material comprising an open weave unbleached muslin base impregnated with a mixture consisting of about one hundred parts by weight of soft adhestive pitch and about. seven parts by weight of mineral oil which is adapted to prevent hardening of the pitch. r i

3. The method of waterproofing a woven fabric Which comprises drawing the fabric slowly through'a bath heated uniformly to a temperature of about C. and consisting of aboutone hundred parts by weight of soft adhesive pitch and about seven parts by weight of mineral oil.

In witness whereof, I have hereunto set my hand this 24th day of June, 1926.

CHARLES H. PANTHEN." 

